1. Field of the Invention
This invention relates to a system and method for determining the probability of failing successfully to complete a mission following a predetermined route through a domain containing a series of threats. For convenience the system and method are referred to herein as a tactical routing system and method.
2. Description of the Prior Art
A tactical routing system finds application, for example, in military aircraft, where it is a great importance for the pilot and his ground controller to be able to estimate with a reasonable degree of accuracy the probability of the aircraft being flown from a base to a target and back to base over hostile territory without the aircraft being destroyed by a ground based missile or gun site. The advent of sophisticated radar and intelligence systems such as those described in our joint European Published Application No. 0173534 now make it possible to locate and identify the nature of a threat in the domain over which the aircraft is to fly. However, although this information may be supplied to the pilot of the aircraft, his very high workload makes it impossible for him to make an accurate assessment of the magnitude of the threat posed by any particular missile or gun site. Still less is he able to predict with accuracy the compound effect of all of the gun and missile sites within range of his path and consequently the probability of failing to reach his desired target without destruction of the aircraft. For convenience, the probability of the pilot failing to survive a given threat is herein termed the "kill probability" and the probability of failing to complete a mission is herein termed the "accumulated kill probability". The term "domain" is used herein to define that geographic region which contains the start and end points of the mission and which is sufficiently large to include any ground based threat which may influence the accumulated kill probability.
In addition to being unable to predict the accumulated kill probability of a particular route, the pilot is also unable to optimize the route taken between the start and end points, and thus the pilot's choice of route may often result in an unacceptably high accumulated kill probability.
Consequently, there exists a need for a tactical routing system which can determine and display a route having an optimal survival probability for an aircraft flying to a target and passing over hostile territory. In addition, since in a military scenario the location and capability of certain of the ground based threats (gun or missile sites) may only be fully determined during the mission, there is also a need for a tactical routing system in which fresh information regarding threats may be supplied to the system to form a rapid update of the optimal route. In this specification, the term "an optimal route" is used to mean a route having a relatively low associated accumulated kill probability, and it is not necessarily the best possible route.